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Abstract:

A vibration-type actuator includes a supporting mechanism functioning
such that a reaction force from a base against a pressing force from a
driven member to an elastic member is dispersed to a vibrating portion
and a supported portion of the elastic member. The supported portion is
supported by the base with a vibration-isolating member interposed
therebetween.

Claims:

1. A vibration-type actuator comprising: an electromechanical energy
conversion element; an elastic member including: a vibrating portion to
which the electromechanical energy conversion element is bonded; a
supported portion provided on a base; and a connecting portion connecting
the vibrating portion and the supported portion to each other; and a
first member having a spring characteristic and provided between the
vibrating portion and the base.

2. The vibration-type actuator according to claim 1, wherein a reaction
force from the base against a pressing force from a driven member to the
vibrating portion is dispersed to the vibrating portion and the supported
portion.

3. The vibration-type actuator according to claim 1, wherein the first
member having a spring characteristic is a felt member.

4. The vibration-type actuator according to claim 2, wherein the first
member having a spring characteristic is a spring.

5. The vibration-type actuator according to claim 4, wherein the spring
is a leaf spring.

6. The vibration-type actuator according to claim 1, further comprising a
second member having a vibration-isolating characteristic and provided
between the vibrating portion and the base.

7. The vibration-type actuator according to claim 6, wherein the second
member having a vibration-isolating characteristic is a
vibration-isolating plate having a projection that supports a portion of
the electromechanical energy conversion element where vibration is small.

8. The vibration-type actuator according to claim 6, wherein the second
member having a vibration-isolating characteristic is a felt member.

9. The vibration-type actuator according to claim 1, further comprising a
third member having at least one of a spring characteristic and a
vibration-isolating characteristic and provided between the supported
portion and the base.

10. The vibration-type actuator according to claim 9, wherein the third
member having at least one of a spring characteristic and a
vibration-isolating characteristic is a felt member.

11. The vibration-type actuator according to claim 9, wherein the third
member having at least one of a spring characteristic and a
vibration-isolating characteristic is a vibration-isolating member having
a projecting portion, and wherein the projecting portion supports a
portion of the supported portion where vibration is small.

12. The vibration-type actuator according to claim 9, wherein the third
member having at least one of a spring characteristic and a
vibration-isolating characteristic is a spring.

13. The vibration-type actuator according to claim 1, further comprising
an equalizer configured to adjust orientations of the electromechanical
energy conversion element and the elastic member with respect to a driven
member, the equalizer being provided between the vibrating portion and
the base.

14. The vibration-type actuator according to claim 13, wherein the
equalizer includes a plate and a ball, the plate having a conical groove.

15. The vibration-type actuator according to claim 1, further comprising
a position-regulating member configured to regulate a position of the
elastic member in a planar direction.

16. The vibration-type actuator according to claim 1, satisfying a
relationship of F3.ltoreq.F1-F0, where F1 denotes a pressing force
applied from a driven member to the elastic member, F2 denotes a reaction
force applied from the base to the vibrating portion, F3 denotes a
reaction force applied from the base to the supported portion, and F0
denotes a lower limit of the reaction force F2 at which the
electromechanical energy conversion element remains bonded to the
vibrating portion.

17. The vibration-type actuator according to claim 1, wherein the
vibrating portion is provided in a recess provided in the base.

18. An image pickup apparatus comprising: an image pickup device; a lens;
and the vibration-type actuator according to claim 1.

19. A stage movable by the vibration-type actuator according to claim 1.

Description:

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a vibration-type actuator, and an
image pickup apparatus and a stage each including the same.

[0003] 2. Description of the Related Art

[0004] There are various vibration-type actuators (for example, an
oscillatory wave motor) in each of which a driven member is driven with
vibrations generated in an elastic member. In an oscillatory wave motor,
a vibrator including an electromechanical energy conversion element (such
as a piezoelectric element) and an elastic member (mostly, a metal
elastic member) that is bonded to the electromechanical energy conversion
element is excited to vibrate in a plurality of vibration modes. With the
combination of the plurality of vibration modes, the surface of the
elastic member undergoes an elliptic movement, whereby the driven member
that is in contact with the elastic member is driven relative to the
elastic member. Various kinds of such oscillatory wave motors have been
proposed. For example, known oscillatory wave motors that rotationally
drive lens barrels included in cameras and the like include a ring-shaped
oscillatory wave motor, a bar-type rotary oscillatory wave motor, and so
forth. Many other motors with improvements in their configurations or
forms have also been proposed, such as an oscillatory wave motor in the
form of a rotary actuator that includes a plurality of flat-plate elastic
members each having a thin-plate vibrating portion and a projecting
portion, the elastic members being arranged along the circumference of
the motor. In addition, many vibration-type linear actuators have been
proposed in each of which a flat-plate elastic member, such as the one
described above, is provided in contact with a linear slider in such a
manner as to be driven linearly.

[0005] An outline of an exemplary oscillatory wave motor, disclosed by
Japanese Patent Laid-Open No. 2011-200053, including a flat-plate elastic
member will now be described. The oscillatory wave motor includes a
vibrator and a slider that is in contact with the vibrator. The vibrator
includes an elastic member and a piezoelectric element. The piezoelectric
element is bonded to the elastic member with adhesive or the like. The
elastic member includes a vibrating portion that vibrates together with
the piezoelectric element, a supported portion that is substantially
insulated from vibration generated in the vibrating portion, and a
connecting portion that connects the vibrating portion and the supported
portion to each other, the connecting portion functioning such that one
end thereof follows the vibration of the vibrating portion while the
other end thereof suppresses the transmission of the vibration to the
supported portion. The vibrating portion has, on one surface thereof, two
projecting portions via which the vibration is transmitted to a driven
member. When alternating-current electric fields with different phases
are applied to the piezoelectric element, the vibrator is excited to
generate two kinds of out-of-plane bending vibrations, whereby the tips
of the two projecting portions each undergo an elliptic movement.
Consequently, the slider that is in contact with the projecting portions
receives a frictional driving force and is thus driven in one direction.

[0006] Meanwhile, Japanese Patent Laid-Open No. 64-34184 discloses an
ultrasonic motor in which the entirety of a vibrator is supported by a
supporting member with vibration-isolating members interposed
therebetween, whereby the loss of vibrational energy is reduced.

SUMMARY OF THE INVENTION

[0007] In Japanese Patent Laid-Open No. 2011-200053, a pressing force is
applied to the driven member and the vibrator by utilizing magnetism.
From the viewpoints of cost reduction and so forth, a configuration, such
as the one illustrated in FIG. 16, including springs for application of a
pressing force may be employed. In the configuration illustrated in FIG.
16, only supported portions 105 are supported by a base 132. Therefore,
an elastic member 102 receives bending stresses acting in direction A
under pressing forces (acting in direction B) generated by leaf springs
106 and applied thereto from a driven member 131. The bending stress may
act as a force that separates a piezoelectric element 103 and the elastic
member 102, which are bonded to each other, from each other. Hence,
considering the service environment, the number of available kinds of
adhesive is strictly limited, leading to a cost increase in some cases.
In the ultrasonic motor disclosed by Japanese Patent Laid-Open No.
64-34184, a stator unit functioning as a vibrating portion is supported
by the supporting member with the vibration-isolating members functioning
as vibration absorbers interposed therebetween. In such a configuration,
a portion substantially insulated from vibration and functioning as a
supported portion cannot receive a pressing force from a driven member,
resulting in a great loss of vibrational energy.

[0008] One aspect of the present invention relates to a vibration-type
actuator in which the occurrence of separation of an elastic member and a
piezoelectric element from each other is suppressed. Another aspect of
the present invention relates to a vibration-type actuator in which the
loss of vibrational energy is reduced.

[0009] For example, according to the one aspect of the present invention,
a vibration-type actuator includes an electromechanical energy conversion
element; an elastic member including a vibrating portion to which the
electromechanical energy conversion element is bonded, a supported
portion provided on a base, and a connecting portion connecting the
vibrating portion and the supported portion to each other; and a first
member having a spring characteristic and provided between the vibrating
portion and the base.

[0010] In the present invention, a vibrating portion refers to a portion
of an elastic member that vibrates together with an electromechanical
energy conversion element.

[0011] Furthermore, in the present invention, a vibrator comprises at
least an electromechanical energy conversion element and an elastic
member, and the vibrator generates mechanical vibrations when a voltage
is applied to the electromechanical energy conversion element.

[0012] Furthermore, in the present invention, a driven member moves
relative to a vibrator when the vibrator vibrates. The relative movements
of the vibrator and the driven member are realized not only when the
driven member moves while the vibrator is fixed but also when the
vibrator moves while the driven member is fixed.

[0013] The vibration-type actuator according to the present invention
includes at least a vibrator. For example, the vibration-type actuator
may include a vibrator and a supporting mechanism that supports the
vibrator. For another example, the vibration-type actuator may include
the vibrator, the supporting mechanism, and a base.

[0014] Further features of the present invention will become apparent from
the following description of exemplary embodiments with reference to the
attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIGS. 1A and 1B illustrate a vibrator.

[0016]FIG. 2 is a perspective view of a vibration-type actuator
illustrating major elements thereof.

[0017]FIG. 3 is a partially exploded perspective view of the
vibration-type actuator illustrated in FIG. 2.

[0018]FIG. 4 illustrates a vibration-type actuator including a
vibration-isolating plate as a substitute for a felt member included in
the configuration illustrated in FIGS. 2 and 3.

[0019]FIG. 5 illustrates a modification of the vibration-type actuator.

[0020]FIG. 6 illustrates another modification of the vibration-type
actuator.

[0021]FIG. 7 illustrates yet another modification of the vibration-type
actuator.

[0022]FIG. 8 illustrates yet another modification of the vibration-type
actuator.

[0023]FIG. 9 illustrates yet another modification of the vibration-type
actuator.

[0024]FIG. 10 illustrates yet another modification of the vibration-type
actuator.

[0029]FIG. 15 illustrates yet another vibration-type actuator including a
felt member as a substitute for a vibration-isolating member included in
the configuration illustrated in FIG. 14.

[0030]FIG. 16 illustrates a supporting mechanism included in a
related-art flat-plate vibrator.

[0031]FIG. 17 illustrates an application of any of the vibration-type
actuators.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

[0032] A first embodiment of the present invention will now be described
with reference to FIGS. 1A to 12. FIGS. 1A and 1B illustrate a
configuration of a vibrator that is common to all embodiments of the
present invention. A vibrator 1 includes an elastic member 2 and an
electromechanical energy conversion element such as a piezoelectric
element 3 that is bonded to the elastic member 2. Herein, the vibrator 1
is a flat-plate vibrator. A flexible printed-circuit board (FPC) 4 is
connected to the piezoelectric element 3 and supplies power to the
piezoelectric element 3. The piezoelectric element 3 is bonded to the
elastic member 2. The elastic member 2 includes a vibrating portion 2-3
that vibrates together with the piezoelectric element 3, supported
portions 2-5 that are substantially insulated from vibration that occurs
in the vibrating portion 2-3, and connecting portions 2-4 that each
connect the vibrating portion 2-3 and a corresponding one of the
supported portions 2-5 to each other. The connecting portions 2-4 each
function such that one end thereof follows the vibration of the vibrating
portion 2-3 while the other end thereof suppresses the transmission of
the vibration to the corresponding supported portion 2-5. The vibrating
portion 2-3 has projecting portions 2-2 functioning as frictional contact
portions on a surface thereof opposite a surface thereof bonded with the
piezoelectric element 3. One of the supported portions 2-5 has a circular
hole 2-6, and the other supported portion 2-5 has an oblong hole 2-7. The
holes 2-6 and 2-7 are to be fitted onto respective pins 8 (see FIGS. 13
to 15 and to be described below), whereby the position of the flat-plate
vibrator 1 in the planar direction is regulated. In the first embodiment,
the holes 2-6 and 2-7 may be used as positioning members to be used in an
assembly process but are not necessary at this stage.

[0033]FIG. 2 is a perspective view of a vibration-type actuator according
to the first embodiment illustrating major elements thereof. FIG. 3 is a
partially exploded perspective view of the ultrasonic motor illustrated
in FIG. 2. In the first embodiment, three sets of flat-plate vibrators 1
and supporting mechanisms that support the respective vibrators 1 are
arranged annularly, and a driven member 31 is driven in directions A-A.
As illustrated in FIGS. 2 and 3, a base 32 has recesses, in each of which
the vibrating portion 2-3 of a corresponding one of the flat-plate
vibrators 1 (the FPC 4 is not illustrated) is provided. The supported
portions 2-5 of each flat-plate vibrator 1 are fixed to the upper surface
of the base 32 by welding, bonding, screwing, or the like. The vibrating
portion 2-3 of the flat-plate vibrator 1 is supported by an equalizing
plate 42 with a felt member 41 interposed therebetween. The felt member
41 suppresses the transmission of vibration from the flat-plate vibrator
1 to the equalizing plate 42 and members provided nearer to the base 32
with respect to the equalizing plate 42, whereby the loss of vibrational
energy is reduced. The equalizing plate 42 is provided on another
equalizing plate 43 with a ball member 44 interposed therebetween. The
equalizing plate 43 is supported by the base 32 with a Z-shaped leaf
spring 45 interposed therebetween. A lower portion of the leaf spring 45
is fixed to the upper surface of the base 32. An upper portion of the
leaf spring 45 is fixed to the lower surface of the equalizing plate 43.
The leaf spring 45 is provided so as to facilitate the setting of a
reaction force acting on the vibrating portion 2-3 against a pressing
force (to be described below) from the driven member 31 to a desired
value. The lower surface of the equalizing plate 42 and the upper surface
of the equalizing plate 43 have conical grooves, respectively. The ball
member 44 fits in the conical grooves, whereby the movement of the
equalizing plate 42 in planar directions (directions C) is regulated
while the equalizing plate 42 and the felt member 41 are equalized in
directions B, illustrated in FIGS. 2 and 3, with respect to the
equalizing plate 43. In FIG. 2, directions B, which are represented by
two double-headed arrows intersecting at 90 degrees, include all
directions defined by an arrow pivoted about a vertical axis by 360
degrees. The driven member 31 includes a frictional contact portion on
one of the two surfaces thereof. The frictional contact portion has
undergone an anti-abrasion process. The driven member 31 is provided such
that the frictional contact portion thereof faces and is in contact with
the upper surfaces of the projecting portions 2-2, which function as
frictional contact surfaces of the flat-plate vibrator 1. The flat-plate
vibrators 1 and the driven member 31 receive appropriate pressing forces
that are applied by three leaf springs 49 and guide members (not
illustrated) for the driven member 31.

[0034]FIG. 4 illustrates a configuration including the base 32 and the
members provided on the base 32 that are the same as those illustrated in
FIGS. 2 and 3 excluding the felt member 41, which is substituted by a
vibration-isolating plate 47. The function of this configuration is the
same as that of the configuration illustrated in FIGS. 2 and 3. The
vibration-isolating plate 47 has projections on a surface thereof facing
the piezoelectric element 3. The projections provide point supports that
support the piezoelectric element 3 at respective positions where the
vibration of the piezoelectric element 3 becomes minimum. The positions
where the vibration becomes minimum include not only positions where the
vibration becomes exactly minimum but also positions where the vibration
falls within a range including the minimum value and errors with respect
thereto that may occur in the manufacturing process and during use. In
this case, the positions where the vibration becomes minimum are the
intersections between nodal lines 11 and 12 and nodal lines 13, 14, and
15 (to be described below referring to FIG. 12). The material for the
vibration-isolating plate 47 may be resin, in terms of vibration
isolation, but is not limited thereto. The vibration-isolating plate 47
also functions as the equalizing plate 42 and has a conical groove
provided in a surface thereof opposite a surface thereof having the
projections. The ball member 44 fits in the conical groove.

[0035] As described above, the vibration-type actuator according to the
first embodiment includes any spring elements as supporting mechanisms
that support each vibrating portion 2-3. The vibration-type actuator
according to the first embodiment may further include any
vibration-isolating elements. For example, the vibration-type actuator
according to the first embodiment may include any members having spring
characteristics as spring elements (for example, the leaf spring 45 and
the felt member 41), and any members having vibration-isolating
characteristics as vibration-isolating elements (for example, the felt
member 41 and the vibration-isolating plate 47). The vibration-type
actuator according to the first embodiment may further include any
equalizers (for example, the equalizing plates 42 and 43 and the ball
member 44) as equalizing elements that cause the reaction force acting
against the pressing force from the vibration-isolating elements and/or
the spring elements to be applied straight to the vibrator. The
equalizers adjust the orientations of the elastic member 2 and the
piezoelectric element 3 so that the vibrator 1 extends along and is in
contact with the contact surface of the driven member 31 under the
pressing force and the reaction force. The felt member 41 functions as
both a member having a vibration-isolating characteristic and a member
having a spring characteristic. Therefore, if the felt member 41 is
employed, the member having a spring characteristic may be omitted in
terms of design. If the motor is not required to have very high energy
efficiency, the members having vibration-isolating characteristics are
not necessarily provided. If the supporting mechanism can be manufactured
with high accuracy and the reaction force acting on the vibrating portion
2-3 is applied straight to the elastic member 2, the equalizers are not
necessarily provided. Considering the above, the supporting mechanism
that supports the vibrating portion 2-3 according to the first embodiment
may be modified as illustrated in FIGS. 5 to 10. FIGS. 5, 6, and 7
illustrate supporting mechanisms including no equalizers. FIG. 8
illustrates a supporting mechanism including no vibration-isolating
members. FIG. 9 illustrates a supporting mechanism that includes a felt
member also functioning as a member having a spring characteristic. FIG.
10 illustrates a supporting mechanism that includes a felt member also
functioning as a member having a spring characteristic but includes no
equalizers. These supporting mechanisms are obtained by omitting any of
the elements that are omittable from any of the supporting mechanisms
illustrated in FIGS. 2, 3, and 4 in accordance with the above guidelines.
Among such configurations, the best one may be selected as the supporting
mechanism by considering all the factors including the required accuracy,
allowable space, manufacturing cost, and so forth concerning the
supporting member. Some of the above modifications of the supporting
mechanism include the following two elements that are not included in the
configurations illustrated in FIGS. 2, 3, and 4. One is a
felt-member-supporting plate 46 that supports the felt member 41. In the
configuration illustrated in FIG. 3, the equalizing plate 42 also
functions as the felt-member-supporting plate 46. Since the configuration
illustrated in FIG. 6 does not include the equalizing plate 42, the
configuration requires the felt-member-supporting plate 46. The other is
a vibration-isolating plate 48 having no conical groove. In the
configuration illustrated in FIG. 4, the vibration-isolating plate 47
also functions as the equalizing plate 42. Since the configuration
illustrated in FIG. 7 includes no equalizing elements, the conical groove
is omitted.

[0036] In the first embodiment, the reaction force acting against the
pressing force from the driven member 31 is made to disperse into the
vibrating portion 2-3 and the supported portions 2-5 of the vibrator 1.
In a case where no spring elements are included in the supporting
mechanism that supports the vibrating portion 2-3, if the relative
difference between the level of the supporting surface of the vibrating
portion 2-3 and the level of the supporting surfaces of the supported
portions 2-5 varies because of manufacturing errors, the reaction force
acting from the base 32 toward the vibrating portion 2-3 and the
supported portions 2-5 may also vary among the different sets of the
flat-plate vibrators 1 and the supporting mechanisms. Hence, the
modifications of the supporting mechanism that support the vibrating
portion 2-3 that are illustrated in FIGS. 5 to 10 all include any members
having spring characteristics. If the above relative difference between
the supporting surfaces is adjusted with high accuracy, the supporting
mechanism that supports the vibrating portion 2-3 does not necessarily
include members having spring characteristics.

[0037]FIG. 11 illustrates forces acting on the flat-plate vibrator 1 (the
gravitational force is ignored). The flat-plate vibrator 1 receives a
pressing force F1 from the driven member 31, the vibrating portion 2-3
receives a reaction force F2 from the base 32, and the supported portions
2-5 together receive a reaction force F3 from the base 32. The lower
limit of the reaction force F2 at which the piezoelectric element 3
remains bonded to the elastic member 2 is denoted by F0. In the first
embodiment, the dimensions of the supporting mechanism and the spring
constant of the leaf spring 45 are set such that a relationship of
F3≦F1-F0 is satisfied. The lower limit F0 is experimentally
obtained in advance. The relationship of F3≦F1-F0 applies to all
of the embodiments of the present invention.

[0038] When an alternating-current electric field is applied from the FPC
4 to the piezoelectric element 3, the flat-plate vibrator 1 is excited to
vibrate in a first vibration mode (mode 1) and a second vibration mode
(mode 2) as illustrated in FIG. 12. Mode 1 is, for example, a first-order
out-of-plane bending vibration mode occurring in the short-side direction
of the flat-plate vibrator 1. The vibration in mode 1 has two nodal lines
(linear portions where vibration nodes reside) 11 and 12 extending in a
direction orthogonal to the short-side direction of the flat-plate
vibrator 1 in FIG. 12, with a vibration loop appearing at the midpoint
between the nodal lines 11 and 12. Mode 2 is, for example, a second-order
out-of-plane bending vibration mode occurring in the long-side direction
of the flat-plate vibrator 1. The vibration in mode 2 has three nodal
lines 13, 14, and 15 that are orthogonal to the two nodal lines 11 and
12. As illustrated in FIG. 12, the projecting portions 2-2 are provided
around positions where the respective nodal lines 14 and 15 pass through.
Therefore, at the tips (upper surfaces) of the projecting portions 2-2,
when the vibration in mode 2 is generated, the amplitude of vibration in
the Z direction is substantially zero while only a certain amplitude of
vibration in the X direction occurs. Meanwhile, at the tips of the
projecting portions 2-2, when the vibration in mode 1 is generated, the
amplitude of vibration in the X direction is substantially zero while the
amplitude of vibration in the Z direction becomes maximum. Hence, if the
vibrations in the two respective modes are generated simultaneously and
are combined together while the phases thereof are appropriately
adjusted, the projecting portions 2-2 of the elastic member 2 undergo
elliptic movements. When the driven member 31 illustrated in FIG. 2 is
brought into contact with the projecting portions 2-2 in such a state,
the driven member 31 is driven in directions A-A with a frictional force
produced by the elliptic movements.

[0039] As described above, the vibration-type actuator according to the
first embodiment includes the supporting mechanism functioning such that
the reaction force from the base against the pressing force from the
driven member to the elastic member is dispersed to the vibrating portion
and the supported portion of the vibrator. Therefore, a separating force
applied to a bonding layer provided between the elastic member and the
piezoelectric element is smaller than in a supporting mechanism in which
the reaction force acts only on the supported portion. Furthermore, the
loss of vibrational energy is smaller than in a supporting mechanism in
which the reaction force acts only on the vibrating portion. Furthermore,
from the viewpoints of bond separation and the loss of vibrational
energy, the best design of the reaction force acting on the vibrating
portion and the supported portion is realized.

[0040] Although the first embodiment concerns a case where three vibrators
are provided on the base, the present invention is not limited to such an
embodiment. One or two vibrators or four or more vibrators may be
provided on the base. Moreover, vibrators may be arranged such that the
vibration-type actuator performs linear driving (in which the driven
member undergoes a linear movement relative to the vibration-type
actuator).

Second Embodiment

[0041] A second embodiment of the present invention will now be described
with reference to FIG. 13. In the first embodiment, the supported
portions 2-5 of the flat-plate vibrator 1 is fixed to the base 32. In the
second embodiment, as illustrated in FIG. 13, the supported portions 2-5
as members having a spring characteristic are supported by the base 32
with leaf springs 51 interposed therebetween. The leaf springs 51 are
fixed to the base 32 and support the supported portions 2-5 of the
flat-plate vibrator 1. The circular hole 2-6 and the oblong hole 2-7
provided in the elastic member 2 are fitted onto the respective pins 8
standing from the base 32, whereby the position of the flat-plate
vibrator 1 in the planar direction is regulated. Hence, the pins 8
function as position-regulating members that regulate the position of the
elastic member. The supported portions 2-5 is not necessarily fixed to
the leaf springs 51. If the supported portions 2-5 and the leaf springs
51 are fixed to the base 32, the pins 8 are no longer necessary. The
elastic member 2 and the leaf springs 51 may be provided as an integral
body. Modifications of the supporting mechanism that supports the
vibrating portion 2-3 are obtained by adding the pins 8 and the leaf
springs 51 and removing the leaf spring 45 to and from any of the
configurations illustrated in FIGS. 3 to 10. In the second embodiment,
the supporting mechanism that supports the vibrating portion 2-3 may
include a member having a spring characteristic. Modifications of the
supporting mechanism that supports the vibrating portion 2-3 also include
a configuration obtained by simply adding the pins 8 to any of the
configurations illustrated in FIGS. 3 to 10.

[0042] As described above, the vibration-type actuator according to the
second embodiment includes the supporting mechanism functioning such that
the reaction force from the base against the pressing force from the
driven member to the elastic member is dispersed to the vibrating portion
and the supported portion of the elastic member. Therefore, a separating
force applied to a bonding layer provided between the elastic member and
the piezoelectric element is smaller than in a supporting mechanism in
which the reaction force acts only on the supported portion. Furthermore,
the loss of vibrational energy is smaller than in a supporting mechanism
in which the reaction force acts only on the vibrating portion.
Furthermore, from the viewpoints of bond separation and the loss of
vibrational energy, the best design of the reaction force acting on the
vibrating portion and the supported portion is realized. Furthermore,
since some of the members having spring characteristics concentratedly
included in the supporting mechanism that supports the vibrating portion
2-3 in the first embodiment are dispersed to a mechanism that supports
the supported portions 2-5, the height of the vibration-type actuator is
reduced.

[0043] Although the second embodiment concerns a case where three
vibrators are provided on the base, the present invention is not limited
to such an embodiment. One or two vibrators or four or more vibrators may
be provided on the base. Moreover, vibrators may be arranged such that
the vibration-type actuator performs linear driving (in which the driven
member undergoes a linear movement relative to the vibration-type
actuator).

Third Embodiment

[0044] A third embodiment of the present invention will now be described
with reference to FIGS. 14 and 15. In the third embodiment, the supported
portions 2-5 of the flat-plate vibrator 1 are supported by the base 32
with vibration-isolating members 61 (see FIG. 14) or felt members 71 (see
FIG. 15) as vibration-isolating elements interposed therebetween. The
elastic member 2 according to each of the first and second embodiments is
designed such that the transmission of the vibration occurring in the
vibrating portion 2-3 to the supported portions 2-5 is suppressed by
providing the connecting portions 2-4. Practically, however, some of the
vibration may be transmitted to the supported portions 2-5. Consequently,
depending on the method of supporting the supported portions 2-5, the
loss of vibrational energy may increase. The third embodiment is suitable
for a case where the high suppression of the loss of vibrational energy
is required.

[0045] Referring to FIG. 14, the vibration-isolating members 61 have
projecting portions, respectively, on the upper surfaces thereof and are
fixed to the base 32. The projecting portions provide point supports at
positions of the supported portions 2-5 where the vibration becomes
minimum. Although each of the vibration-isolating members 61 illustrated
in FIG. 14 has one projecting portion, the present invention is not
limited to such an embodiment. Any number of projecting portions may be
provided at any positions where the vibration becomes minimum. The
positions where the vibration becomes minimum include not only positions
where the vibration becomes exactly minimum but also positions where the
vibration falls within a range including the minimum value and errors
with respect thereto that may occur in the manufacturing process and
during use. The circular hole 2-6 and the oblong hole 2-7 provided in the
elastic member 2 are fitted onto the respective pins 8 standing from the
base 32, whereby the position of the flat-plate vibrator 1 in the planar
direction is regulated. Hence, the pins 8 function as position-regulating
members that regulates the position of the elastic member.

[0046]FIG. 15 illustrates a configuration in which the
vibration-isolating members 61 are substituted by the felt members 71
that are interposed between the base 32 and the supported portions 2-5.
The other elements are the same as those illustrated in FIG. 14, and
detailed description thereof is omitted.

[0047] Modifications of the supporting mechanism that supports the
vibrating portion 2-3 are obtained by adding the pins 8 and the
vibration-isolating members 61 or the felt members 71 and removing the
leaf spring 45 to and from any of the configurations illustrated in FIGS.
3 to 10, and by adding the pins 8 and the vibration-isolating members 61
or the felt members 71 to any of the configurations illustrated in FIGS.
3 to 10. Furthermore, both the vibration-isolating members 61 and the
felt members 71 may be provided.

[0048] As described above, the vibration-type actuator according to the
third embodiment includes the supporting mechanism functioning such that
the reaction force from the base against the pressing force from the
driven member to the elastic member is dispersed to the vibrating portion
and the supported portion of the elastic member. Therefore, a separating
force applied to a bonding layer provided between the elastic member and
the piezoelectric element is smaller than in a supporting mechanism in
which the reaction force acts only on the supported portion. Furthermore,
the loss of vibrational energy is smaller than in a supporting mechanism
in which the reaction force acts only on the vibrating portion.
Furthermore, from the viewpoints of bond separation and the loss of
vibrational energy, the best design of the reaction force acting on the
vibrating portion and the supported portion is realized. Furthermore, the
loss of vibrational energy that may occur because the vibrator is
supported is reduced.

[0049] Although the third embodiment concerns a case where three vibrators
are provided on the base, the present invention is not limited to such an
embodiment. One or two vibrators or four or more vibrators may be
provided on the base. Moreover, vibrators may be arranged such that the
vibration-type actuator performs linear driving (in which the driven
member undergoes a linear movement relative to the vibration-type
actuator).

Fourth Embodiment

[0050] An application of the vibration-type actuator according to any of
the above embodiments will now be described with reference to FIG. 17.
FIG. 17 is a conceptual top view of an image pickup apparatus. An image
pickup apparatus 80 illustrated in FIG. 17 includes a camera body 83 and
a lens barrel 87. The camera body 83 includes a power button 81 and an
image pickup device 82. The lens barrel 87 includes lenses 84, a base 85,
and a vibration-type actuator 86. The lens barrel 87 is an
interchangeable lens unit and is interchangeable with any other
interchangeable lens unit for the camera body 83 in accordance with an
object of shooting. The vibration-type actuator 86 may be any of the
vibration-type actuators according to the first to third embodiments.

[0051] If any of the vibration-type actuators according to the first to
third embodiments is included in the image pickup apparatus 80, there are
provided a wide variety of material options for the adhesive to be
provided between the elastic member and the piezoelectric element
included in the vibration-type actuator, whereby a cost reduction is
realized. Furthermore, since the loss of vibrational energy is reduced,
the power consumption is reduced correspondingly.

[0052] Although FIG. 17 illustrates the image pickup apparatus 80 as an
exemplary application of the vibration-type actuator according to any of
the embodiments of the present invention, the vibration-type actuator
according to any of the embodiments of the present invention is also
applicable to the moving of a stage included in a microscope and other
apparatuses. Such a stage is movable by the vibration-type actuator
according to the present invention.

[0053] According to one aspect of the present invention, the
vibration-type actuator functions such that the reaction force from the
base against the pressing force from the driven member to the elastic
member is dispersed to the vibrating portion and the supported portion of
the vibrator. Therefore, a separating force applied to a bonding layer
provided between the elastic member and the piezoelectric element is
smaller than in a supporting mechanism in which the reaction force acts
only on the supported portion. Furthermore, the loss of vibrational
energy is smaller than in a supporting mechanism in which the reaction
force acts only on the vibrating portion. Furthermore, from the
viewpoints of bond separation and the loss of vibrational energy, the
best design of the reaction force acting on the vibrating portion and the
supported portion is realized.

[0054] While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is not
limited to the disclosed exemplary embodiments. The scope of the
following claims is to be accorded the broadest interpretation so as to
encompass all such modifications and equivalent structures and functions.

[0055] This application claims the benefit of Japanese Patent Application
No. 2012-155513, filed Jul. 11, 2012, which is hereby incorporated by
reference herein in its entirety.